Seven US soldiers were killed amid rising violence in the Afghanistan war, as well as a parliamentary candidate and five campaign workers. President Karzai's chief of staff also said the US must alter its strategy to defeat the Taliban.

Seven US soldiers were killed Saturday and Sunday in Afghanistan, in a violent weekend that deepened concerns about security ahead of September elections. A senior Afghan official also raised fresh questions about US strategy in defeating the insurgency.

Over the weekend, a candidate for parliament was killed by insurgents and the bodies of five campaign workers for a female parliamentary candidate were found. About eight civilians also died.

Violence has risen as more US troops arrive in Afghanistan, bringing the number to about 100,000. The troop increase is part of an attempt to bring the Taliban insurgency under control before July 2011, when President Obama has pledged US troops will begin to withdraw. NATO troops are also attempting to bring about stability before parliamentary elections are held on Sept. 18.

The Associated Press reports that two US soldiers were killed in bombings Sunday in southern Afghanistan, where NATO troops are waging a fierce campaign for control of the Taliban’s stronghold. Two more soldiers were killed in a separate bomb attack in southern Afghanistan, and three were killed in fighting in eastern regions.

On Sunday, Herat residents discovered the bodies of the five workers for parliamentary candidate Fawzya Galani, one of Afghanistan’s few female candidates. The campaign workers were kidnapped Wednesday while traveling in the countryside, according to the Associated Press.

Also in the wave of attacks this weekend, the Washington Post reports that NATO soldiers repelled attacks by Taliban insurgents wearing American uniforms on two bases in the southern Khost Province. One of the bases, Camp Chapman, is where a suicide bomber killed seven CIA employees in December. No US soldiers were killed in Saturday’s attacks, while 21 insurgents died. The AP reports that US officials blamed the Haqqani network for the attack, a Pakistan-based group with ties to Al Qaeda.

The Post reports that Afghan President Hamid Karzai’s chief of staff said over the weekend that he is not confident that Afghanistan is “on a path to success” in defeating the Taliban. He said the US needs to alter its strategy, and also said media reports of a faltering US-Afghan relationship are harming the war effort.

While stressing that the Karzai government is committed to a significant NATO troop presence, Daudzai called on the international forces to stop invasive night raids on residents' homes and to distance their soldiers from "the daily life of the people," a sharp divergence from Gen. David H. Petraeus's strategy of having soldiers embedded in communities. The coalition policies have undermined Karzai's authority and Afghan sovereignty, Daudzai said, and led to "blame games" between the two sides.

While Mr. Daudzai blamed US policy for hurting the effort to defeat the Taliban insurgency, US officials insist that government corruption is one of the largest impediments to success. NPR reports that a recent poll of Afghan men, conducted by the International Council on Security and Development, found that about three-quarters of the men surveyed said government officials in their areas were linked to the insurgency or drug traffickers. About the same percentage said they were opposed to working with foreign forces.